PB2417: PRESENCE´S IMPACT OF NON-SPECIFIC ANTI-HLA ANTIBODIES ON THE DEVELOPMENT OF PRIMARY GRAFT FAILURE IN PATIENTS UNDERGOING PERIPHERAL BLOOD HAPLOIDENTICAL HSCT, EXPERIENCE AT A CENTER IN MEXICO.
Authors: Juan Daniel Garza Escobar, Severiano Baltazar Arellano, Guillermo Sotomayor Duque
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: In haploidentical hematopoietic stem cell transplantation (HSCT), one of the most important factors is to carry out an adequate graft, involving HLA compatibility between the donor and recipient. Given the disparity in this modality, another factor is presented that can contribute to the failure to carry out an adequate graft, such as non-specific anti-HLA antibodies, conditioning primary graft failure (PGF), which leads to a decrease in overall survival. Aims: to demonstrate the impact of the presence of anti-HLA antibodies in patients undergoing haploidentical HSCT on overall survival. Methods: this retrospective, analytical, and cross-sectional study included patients who underwent haploidentical HSCT, for benign and malignant pathologies, from January 2018 to December 2021 in the hematopoietic stem cell transplant unit of the IMSS UMAE# 25 Using measures of central tendency, the proportions between groups were compared using Fisher’s exact test. Univariate and multivariate factor analysis for FIP was performed. Survival analysis was performed using the Kaplan-meier method for overall survival (OS). Results: A total of 87 patients were included, 59 (67.8%) were men, 28 (32.3%) women, the mean age was 21.6 years (1-64 years). The infusion of progenitors was performed fresh in 85 patients (97.7%) and only 2 were cryopreserved (2.3%). It should be noted that no patient with PGF had an infusion of cryopreserved cells. Anti-HLA was present in 45 patients (51.7%). PGF was reported in 11 (12.6%) of the 87; of these, 90% presented anti-HLA. The type of Anti-HLA against most frequently was class I in 2 patients (20%), class II in 1 (10%) and for both in 7 subjects (70%). Of the 59 men, 31 presented anti-HLA (60%) and 13 of the 28 women (46%). No statistical association of sex was found with the presence of Anti-HLA (Fisher’s Test p= 0.651). The presence of anti-HLA and PGF was predominant in the male sex (80%). The most common type of disease involved in PGF was malignant. The mean CD34+ was 14.69 x10^6. The mean number of grafting days for granulocytes was 16.3 days and for platelets 18.4 days. Of the variables analyzed such as ABO incompatibility (p= 1.000), radiotherapy prior to HSCT (p=0.89), benign/malignant disease (p= 0.314), disease activity prior to HSCT (p=0.679) and female donor (p=1.000), it was found that the presence of Anti-HLA had a greater association with PGF (OR 12.353 95% CI 1.506-101.358, p= 0.007). The range in which the anti-HLA levels were found was 1,000-2,000 IF. Only 3 presented specific anti-donor antibodies, with titers below 2,000 IF and none of these patients presented PGF. The mean follow-up was 14.4 months (range 1-48 months). Of the total number of patients, 11 died of complications associated with PGF (12.6%) and 23 (26.4%) died from situations unrelated to PGF. The type of pathology most associated with PGF was malignant pathology (81.8%) headed by AML (36.3%), followed by ALL (18.1%), MDS (9%) and HL (9%), marrow failure on the benign side I present an 18.1% PGF. The presence of anti-HLA is associated with a worse outcome (HR= 2,576; 95% CI 1,250-5,308). presenting a lower OS, compared to those who did not present PGF. The median survival was 35 months for those without anti-HLA and 20 months with anti-HLA. The 4-year OS was 20% with anti-HLA and 68% without Anti-HLA. Summary/Conclusion: the results obtained in our center demonstrate the impact of the presence of anti-HLA antibodies in patients undergoing haploidentical HSCT, contributing to PGF, as well as mortality related to it.Keywords: Allogeneic hematopoietic stem cell transplant, Haploidentical stem cell transplantation, Allogeneic peripheral blood stem cells, Haploidentical